Circuit-opening device for electric heaters.



No. 839,255. PAIENTED DEC. 25, 190C.

` III. AYEE. CIRCUIT OPENING DEVICE ECE ELECTRIC HEAIEES.

APPLICATION FILED MAY5,1905.

15gg.. f.

Lpnf @Mmm ZWEI zo ya vessel for heat-' i UNITED STATES PATENT OFFICE.' f

J AMES l. AYER, OF CAMBRIDGE, MASSACHUSETTS, ASSIGNOR TO SIMPLEX ELECTRIC HEATING- COMPANY, OF BOSTON, MASSACHUSETTS, A COR- roEATioN oF MASSACHUSETTS.

CIRCUIT-OPENING DEVIC FORELEGTRIC HEATERS.

' i Specication of Lettera Patent.

PatontedDec. 25, 1906.

Appiimiopnia iny 5, 190s. sei-minstens.

i representing like parts.

It is the object of this invention to protectan electricall -lieated device from in ury or destruction due t'o overheating. This object is secured by the provision of a -circuit- Aopening device operated by a redetermined l, dangerous temperature ofthe cated device.

The invention may be embodied in vari- .ous electricall -heated devices.

The invention is here shown embodied in water or other-li uids. It is generally desired that such a-4 evice shall operate very quickly, and it is therefore rovidedwith apowerful electric heater of arge capacity as compared with the area 2 5 heated in or er to produce quick results in' heating or boiling water. Such a vessel if v'operated without' the liquid easily becomesoverheated in a short time and is either seriously injured or destroyed by such over- 3ob heating. The present invention guards against injury or destructionof the heaterl .under these conditions by insuring the opening of the electric circuit when a dangerous Y Y ten'liperature. of the vessel has been attained. t

e drawings-show the invention as embodied inan o n vessel more particularly for heating liquids and illustrate theprotective device in two different forms.

In the drawings, Figure 1 is a` central ver- 4o' tical cross-section of a vessel for heatingliquids'v embodying' one form of. the invention.

l n 2 is a bottom plan view of the construe-- tion shown in Fig. 1. Fig. 3 is a viewv of the veel, similar to that shown in Fig. 1,. par- 45 tially broken awa and providedwith a prov 5o the .heating of li tectivedevice of 'fferent forni. -1 Fig. 4 isa -bottom plan view of the construction shown in Fig.' 3.'A A Arepresentsv ano ui s or other substances',u 'shown ,as `made oli sheet metal. The vessel ii vessel adapted fai-i" A is provided at the bottom with a chamber B, here shown as formed by the addition of a falsebottom C to the vessel A. In this chamber and attached to the vessel A is-located the electric resistance D, the terminals of which, E E, passent to the exterior of the chamber for' connection to the supplying-circuit.- In the chamber -B is located the circuitopening device, which in this form of the invention is shown as a metallic block F, at-

tachedto one of the terminals E below a break in the saine by a fusible solder G.

Below the block an opening is provided in the chamber B with a removable cover H.

-When the Yelectric current is supplied to the-device shown, anyliquid or other substance should be heated in the usual manner in the-vessel A. If, however, through neglect or otherwiseY the contents of 'the vessel A should boil awa evaporate, or if the vessel should not be fil ed in the first place, then the current being continually supplied the v would soon become overheated and eventually seriously in'ured or entirely destroyed. Before the vesse vA attains a dangerous teinperature the heat in the vessel is communicated to the solder. The surrounding air, and

preferably, as in theV resent ca se, the air of,v

acts to conduct the' The terminals connect-- ing the solder and the heating-coil serve. also an inclosed chamber heat to the solder.

to conduct the at.. When the heat rises sufficienti to melt the solder, the blockF of course falls .by gravity and the circuit is openid, preventing further' heating ofA the vesse i In the other forni of the invention (shown in Fi 3 and4) a similar vessel A is illustrate provided with a similar chamber B at its base, formed by inserting the false bottom C in the vessel." f

' The heat resistance D andthe terminals i -postsKK at abrealtinV i This fuse, otherready described, the .vessel A approximates a dangerogs temperature, due overheatprotection-,against unusual occurrences and struction to the vessel, has infrequent occaing, the heat conveyed through the air, and l preferably the air of the inclosed chamber B', y and also along the-terminals from the heater, penetrating the conducting-shell L, acts to melt the fuse and open the circuit. j The fuse being contained in the shell L, any arc formed by the break in the circuit will not injure the vesselV or cause 'an -explosion or other undesirable results.

VAn opening is provided in the bottom of the chamber B adjacent to the fuse and has a removable cover H. j

In both forms of the invention illustrated when the circuit-opener has acted it is destroyed and has to be replaced.

Adevice of this characten' designed as a arranged to prevent vserious injury 'or 'deslon for operation.. .It may therefore be replaced-by the return of the vessel to the factory or by a skilled mechanic, although in some forms it 'may be arranged for replacement in amore simple manuel'. In the form shown in Figs. 1 and 2 the block must be resoldered ign position, 'and in the form shown in Figs. 3 and 4 a new fuse must be placed in positlon. The cover H or Hinay be fastened mechanically orsoldered in position when a more permanent fasteni is secured. While the invention has been il ustrated in two forms, it may be embodied in other con-- st ructions, and other circuit-opening devices may be employed so long as the are actuated by the heatof the vessel itself transmitted to the circuit-opening device.

Having described my invention, what If claim as new, and desire to secureby Letters Patent, is-

1'. Anelectrically-heated device, a fusible circuit-opener located adjacent to but out of 1 contact with the heated device whereby upon the overheating of the device the circuit will be openedand the devicel protected from injur l il). An electrically-heated device comprising in its construction an auxiliary .closed air-chamber ,a fusible circuit-opener located within said air-chamber and adjacent to but' out of contact with the heated device, Whereby upon theovcrheating of the device the circuit will bev opened and the device protected `from injury.

3. An electrically-heated device comprislng 1n its Iconstructlon an auxiliary closed* soA air-chamber, a fusible circuit-opener located v ELIZABETH M'. CONLIN, DORA A., PRoc'roR. 

